During photosynthesis, G3P from the Calvin cycle is used to produce the monosaccharide . Some of these are converted into the monosaccharide . The two monosaccharides are joined together to form the disaccharide that is transported out of the leaves to other parts of the plant. When photosynthesis is happening rapidly, there is not enough transport out of the cells. So the sugars are stored temporarily in the leaves as the polymer . At night, the polymers can be broken down and transported out of the leaves.